In article ,
Fat Freddy wrote:
I rigged up a drip system for my tomatoes using 1GPH drip emitters, but
I'm not sure about the time or frequency to run the water. I read about
someone else in this area (Sacramento, CA) who used a drip system and
they had 4 -1GPH emitters on each plant and they ran it 3 hours every 5
days. That puts about 12 gallons of water on each plant each week.

My system has 1 emitter per plant and I have been running it every
other day for 2 hours. That puts about 6 gallons of water on each
plant.

I know tomatoes usually need between an inch and two inches of water a
week, but I don't know how to translate that to 1GPH drip emitters.

Can anyone give me some hints?

You need an equivalent surface area to calculate volume from depth;
then consider that 1 gallon = 231 in^3. If you used, for example,
a radius of 18", then each inch of depth would be equivalent to:

pi * r^2 * h (volume of cylinder)

~1017 in^3

~4.4 gallons

This approximation ignores diffusion to areas away from the plant,
rate of drainage (soil type), surface and air temperature (evaporation
and transpiration rates), and many other un-named factors.

We use lots less water than most -- but mulch and a cooler climate
help a lot. You can adjust the amount of water based on how well
the plant does on your initial guess.

-frank
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